How to hide bones in animation
You cannot use a bone for this, but you can use the associated vertex group with a mask modifier.
1st add a Mask modifier to your mesh.
  

Then choose the vertex group in the list
  

Invert the mask with the double arrow button
  

You can animate the renderability by keyframing the "renderable" (camera) button (and viewport visibility with the eye icon)


The mask modifier doesn't use precise weights, it's just yes/no so if a vertice has 0.01 weight, it will be completely hidden.